1. Field
Exemplary embodiments of the present invention relate to a semiconductor device, and more particularly, to a semiconductor device with an air gap and a method for fabricating the same.
2. Description of the Related Art
In general, a semiconductor device includes a second conductive structure formed with an insulation layer provided between a plurality of first conductive structures. For example, the first conductive structure may include a gate, a bit line, a metal interconnection and the like, and the second conductive structure may include a contact plug, a storage node contact plug, a bit line contact plug, a via and the like.
With high integration of the semiconductor device, a distance between the first and second conductive structures has gradually decreased. Accordingly, parasitic capacitance between the first and second conductive structures is increased. With the increase of parasitic capacitance, the operation speed of the semiconductor device is reduced, and the refresh characteristic of the semiconductor device is degraded.
In order to reduce parasitic capacitance, the dielectric constant of the insulation layer may be reduced. In general, an insulation layer used in a semiconductor device may include silicon oxide and silicon nitride. The silicon oxide has a dielectric constant of about 4, and the silicon nitride has a dielectric constant of about 7.
Since the silicon oxide and the silicon nitride have high dielectric constants, they have a limitation in reducing parasitic capacitance. Recently, materials having relatively low dielectric constants have been developed, but the dielectric constants thereof may be not so low.